Water may contain many different kinds of contaminants including, for example, particulates, harmful chemicals, and microbiological organisms, such as bacteria, parasites, protozoa, and viruses. In a variety of circumstances, these contaminants must be removed before the water can be used. Any harmful contaminants must be removed from water before it is potable, i.e., fit for human consumption.
In many instances, there are deadly consequences associated with exposure to contaminated water. In many situations, such as an undeveloped country or a war zone, there are several factors that contribute to contaminated water, including: increasing population densities, increasingly scarce water resources, no water filter utilities, and often, no electricity (including batteries, which may be too expensive). Also, it is common for sources of drinking water to be in close proximity to human and animal waste, such that microbiological contamination is a major health concern. As a result of waterborne microbiological contamination, an estimated six million people die each year, half of which are children under 5 years of age.
In 1987, the U.S. Environmental Protection Agency (EPA) introduced the “Guide Standard and Protocol for Testing Microbiological Water Purifiers”. The protocol establishes minimum requirements regarding the performance of drinking water filter devices that are designed to reduce specific health related contaminants in public or private water supplies. The requirements are that the effluent from a water supply source exhibits 99.99% (or equivalently, 4 log) removal of viruses and 99.9999% (or equivalently, 6 log) removal of bacteria against a challenge. Under the EPA protocol, in the case of viruses, the influent concentration should be 1×107 viruses per liter, and in the case of bacteria, the influent concentration should be 1×108 bacteria per liter. Because of the prevalence of Escherichia coli (E. coli, bacterium) in water supplies, and the risks associated with its consumption, this microorganism is used as the bacterium in the majority of studies. Similarly, the MS-2 bacteriophage (or simply, MS-2 phage) is typically used as the representative microorganism for virus removal because its size and shape (i.e., about 26 nm and icosahedral) are similar to many viruses. Thus, a filter's ability to remove MS-2 bacteriophage demonstrates its ability to remove other viruses.
In undeveloped countries, disaster areas, and in war zones, the water sources may include seawater, rivers, streams, lakes, ponds, ground water, indigenous wells, or sub-standard municipal water. Good water sources may go bad leaving inadequate sources of water or the sources of water may never have been good.
People in these situations may not be educated and may not have shelter, much less a home or place to store a device. Today's solutions seem to be rather large and complex to use. Most solutions purify 5-10 gallons of water and require the user to carry a large container as well as a heavy mechanism which is used to purify water. Individuals probably would not carry a filtration system with an attached 10 gallon water canister in such situations. As a result of not carrying the big solution, many times the individuals in effected areas will drink unpurified water when thirsty, thereby increasing the chances of sickness or even death from unpotable water.
In addition, many solutions require a power source. In a disaster situation or in a war zone, power may not be available. In addition, battery power can be used, however batteries often do not last for a long time and may discharge before the disaster is over or before a soldier or unit of soldiers leaves the area or can find power. Such solutions are heavier, since batteries are not light. This solution also requires a rescue worker, soldier, or unit of soldiers to carry additional batteries. Without batteries, these water purification devices are generally useless. This again leads to people drinking unpotable water is certain situations.